1. Dirac, P.A.M.: Proc. Roy. Soc. (London), Ser. A167, 148 (1938)
2. See for example: Rohrlich, F.: Classical Charged Particles. Reading, Mass.: Addison-Wesley 1965, and standard textbooks on classical electrodynamics
3. Wildermuth, K.: Z. Naturforschung10a, 450 (1955)
4. See e.g. Gromes, D., Petzold, J.: Z. Physik199, 299 (1967)
5. Erber, T.: Fortschr. Physik9, 343 (1961), especially p. 378